Inpatient and outpatient therapy often requires the administration of an intravenous solution or other liquid agent to a patient through a device such as a catheter to permit infusion of a solution, medicament, or other liquid agent as required. The rate of flow of solution into the patient's body is an important variable which can be affected by the pressure of the solution supply and the fluid viscosity.
A system for administering a liquid agent to a patient is disclosed in the commonly assigned, copending U.S. patent application Ser. No. 08/125,979 filed Sep. 23, 1993.
The administration system accommodates infusion with a controlled, predetermined fluid flow. The system includes a solution or other liquid agent supply container, a tubing set, and a laser drilled orifice flow restrictor.
The supply container may be a collapsible bag for the self-contained, pressurized type of mobile patient solution administration. The supply container has a fluid port to which is connected a tubing set that includes a length of tubing. A restrictor body and housing is mounted to the end of the tubing. An orifice is located within the body interior. The housing includes a typical snap-nut Luer lock fitting connector. The male end is in fluid connection with the tubing set. The female fitting of the Luer lock connector can be connected in fluid communication with a catheter for patient infusion of the solution or other agent.
The orifice is a generally cylindrical, small diameter passage drilled by laser through a wall or plate of the restrictor which creates a boundary between the inlet and outlet ports of the restrictor. The passage has a predetermined cross-sectional flow area and defines a flow control passage. The restrictor also defines an outlet passage downstream of the flow control orifice.
The orifice plate is relatively thin. However, the thickness is dependent upon the diameter of the orifice drilled therethrough. The actual orifice diameter will vary as required by the precise flow of solution for the particular patient's requirements.
The orifice flow restrictor delivers a predetermined and accurate flow of solution to a patient. Unlike capillary restrictors, the orifice restrictor is relatively unaffected by minor variations in supply solution pressure or viscosity. Moreover, because of the interrelationship between solution feed viscosity and temperature, the orifice restrictor is also relatively unaffected by minor variations in temperature as well.
Although the above-described administration system functions well in many applications, it would be desirable to provide an improved system that could be used to accommodate use with pressurized cuff solution feed containers and/or that would provide an improved priming capability.
For example, in order to administer the liquid agent, the flexible container is inserted into a conventional pressurization cuff. Before the tubing is connected to the catheter, the cuff is pressurized to force the liquid agent out of the container and through the tubing to bleed air from the tubing and other components (e.g., filters, valves, and fittings) until the liquid agent fills the entire system.
Typically, before connecting the administration set to the catheter, the patient bleeds and primes the system by pressurizing the cuff and watching for a drop of the liquid agent to be discharged from the end fitting on the tubing as an indication that all of the air has been bled out of the system. If the end fitting employed on the tubing is the above-described flow restrictor, then some of the pressurized liquid agent can be forced out of the flow control orifice following the last portion of the air being bled out of the system.
Under high cuff pressures, the liquid agent may have a tendency to squirt or stream out of the orifice (prior to the restrictor housing being connected to the catheter). This may result in the undesirable loss of some of the liquid agent. If the system is misused or not otherwise handled in accordance with proper procedures, then unnecessary and undesirable contact between the fluid and the patient may occur prior to the restrictor housing being connected to the catheter.
Accordingly, it would be desirable to provide an improved system which would prevent or minimize streaming or squirting of a liquid agent from the restrictor housing, at least prior to connection of the restrictor housing with the catheter.
It would also be desirable to provide an improved system which could function over a range of low and high pressures.
Additionally, it would be beneficial if such an improved system could be embodied in designs having a relatively low manufacturing cost and a relatively high operational reliability.
The present invention provides an improved flow control device which can accommodate designs having the above-discussed benefits and features.